"""This model provides the BT (Blandford & Teukolsky 1976, ApJ, 205, 580) model.
"""
from pint import ls,GMsun,Tsun
from .stand_alone_psr_binaries.BT_model import BTmodel
from .pulsar_binary import PulsarBinary
from . import parameter as p
from .timing_model import Cache, TimingModel, MissingParameter
import astropy.units as u
[docs]class BinaryBT(PulsarBinary):
"""This is a PINT pulsar binary BT model class a subclass of PulsarBinary.
It is a wrapper for stand alone BTmodel class defined in
./stand_alone_psr_binary/BT_model.py
All the detailed calculations are in the stand alone BTmodel.
The aim for this class is to connect the stand alone binary model with PINT platform
BTmodel special parameters:
GAMMA Binary Einsten delay coeeficient
"""
def __init__(self):
super(BinaryBT, self).__init__()
self.binary_model_name = 'BT'
self.binary_model_class = BTmodel
self.add_param(p.floatParameter(name="GAMMA", value=0.0,
units="second",
description="Time dilation & gravitational redshift"),
binary_param = True)
# remove unused parameter.
self.remove_param('M2')
self.remove_param('SINI')
[docs] def setup(self):
super(BinaryBT, self).setup()
# If any necessary parameter is missing, raise MissingParameter.
# This will probably be updated after ELL1 model is added.
for p in ("PB", "T0", "A1"):
if getattr(self, p).value is None:
raise MissingParameter("BT", p,
"%s is required for BT" % p)
# If any *DOT is set, we need T0
for p in ("PBDOT", "OMDOT", "EDOT", "A1DOT"):
if getattr(self, p).value is None:
getattr(self, p).set("0")
getattr(self, p).frozen = True
if getattr(self, p).value is not None:
if self.T0.value is None:
raise MissingParameter("BT", "T0",
"T0 is required if *DOT is set")
if self.GAMMA.value is None:
self.GAMMA.set("0")
self.GAMMA.frozen = True
# If eccentricity is zero, freeze some parameters to 0
# OM = 0 -> T0 = TASC
if self.ECC.value == 0 or self.ECC.value is None:
for p in ("E", "OM", "OMDOT", "EDOT"):
getattr(self, p).set("0")
getattr(self, p).frozen = True